The present invention concerns a device for electroacoustic diffusion comprising diaphragms, balances, and trumpets, made out of balsa wood or mixtures including balsa wood.
It is well known that electroacoustic diffusers, also called loudspeakers, transform electric signals into acoustic energy by means of the vibration of a diaphragm, which usually has a conic shape, a dome-shape, or a planar shape.
The material used for constructing the membrane is fundamental for obtaining the desired electroacoustic features. Research for obtaining the best response from the point of view of the electroacoustic effects, the psychoacoustic effects, and the tone-color of the sound, has led to the use of materials that have various determined features like lightness and non-deformability.
The lightness property allows one to obtain correct reproduction of the high frequencies, while the non-deformability property determines the ability of the material to be exposed to considerable acoustic pressures without distortions due to deformations of the material.
It is easy enough to find materials with the above mentioned features; the use of materials derived from aerospace technologies has allowed one to obtain optimal electroacoustic features, but these materials confer a particular tone-color which often makes the sounds sound reproduced and far removed from a natural tone-color.
One of the reasons that has led to the use of cellulose--which is at present the most widely used material--is that its tone-color is the most natural if compared with other materials that are more rigid and heavy.
Also mixtures of metal and synthetic materials have been used, and this was always with the purpose of obtaining lightness, non-deformability, and correct tone-color.
The main problem remains one of obtaining a non "colored" sound, i.e., the most natural possible sound and, where it may be accepted, a pleasant coloring.
For getting as near as possible to a natural reproduction of the sound, membranes have been developed out of fir-wood, which, even if they are very rigid, have a correct tone-color. These membranes, however, have the problem of being heavy, which prevents one from obtaining acceptable speeds at those frequencies that are not low.
Diffusers have been produced with vibrating wood stripes of different lengths, so as to have different masses according to the frequency to be reproduced, but the dynamic, i.e., the capacity of obtaining quick variations of acoustic pressure, is rather reduced due to the physical structure of the diffuser, because the stripes always have considerable inertia due to their total weight.